In order to explore the blast-induced crack propagation behavior in rock mass with two vertical prefabricated defects, a series of blasting experiments of models with double vertical cracks were carried out based on digital laser caustics. The evolution process of blast-induced crack is shown and the effect of single-hole charge on the crack propagation behavior (crack propagation length, stress intensity factor, propagation velocity, and initiation time, et al) in rock mass with defects was explored. The results show that the crack propagation length, propagation velocity, crack initiation toughness and stress intensity factor at the end of the double vertical cracks increase with the increase of single-hole charge. For crack J_u, the effect of single-hole charge on crack propagation velocity is small, and the limit velocity of crack propagation is about 0.38 times of the shear wave velocity. For cracks D_l and D_r, the initiation time decreases, but the peak stress intensity factor increases with the increase of single hole charge. Besides, the stress intensity factor and propagation length of crack D_r increases significantly compared with crack D_l. The crack D_l starts to crack earlier than the crack D_r when the energy of the blasting stress wave acting on both ends of defect B is enough to cause the crack to propagate on both sides. The increase of charge in a single hole can increase the propagation velocity of crack D_r, but has little effect on the propagation velocity of crack D_l.

It is prone to occur dynamic disasters such as roof falling, sidewall slabbing and rock burst under dynamic disturbance of mechanical percussion drilling and explosive blasting in the roadway with hard rock. It is extremely meaningful to investigate the dynamic load effect on roadway deformation and failure mechanism. To understand the mechanical behavior of roadway surrounding rock under dynamic disturbance, a hard rock roadway was simplified as a hole in rock. And then, a series of impact tests were conducted on prismatic sandstone rock specimens with a hole by a modified split Hopkinson pressure bar testing system to explore the influence of hole size and shape on the dynamic mechanical properties, failure mode and energy dissipation characteristics. The results show that the existence of the hole has significant weakening effects on the dynamic strength, dynamic elastic modulus and peak strain. The dynamic mechanical properties of the rock decrease significantly with the increase of hole size. Among the specimens with different hole shapes, the dynamic strength and peak strain of the square-holed specimens are the largest, followed by the horseshoe-holed and the circle-holed specimens, but their elastic moduli show opposite results. In terms of rock failure modes, splitting tensile and tensile-shear failure occur respectively in intact specimens and pre-holed specimens under impact load. Additionally, the energy consumption density and fractal dimension of the horseshoe-holed specimens are the largest, which are 1.94 J/cm³ and 2.11 J/cm³, respectively. It indicates that the failure process is the most intense for the horseshoe-holed specimens, while the fragmentation degree of the circle and square holed specimens is not much different.

Blasting is widely used in tunnel engineering as a large scale and high efficiency method of rock breakage, but it inevitably brings some bad effects to the adjacent structures and surrounding rocks, among which blasting vibration is the first. Electronic detonator initiation can realize the active control of blasting vibration intensity and spectrum due to its accurate delay, high reliability and safety, which is an effective means to reduce the seismic effect of blasting. In order to explore the influence of the location and number of electronic detonators on the frequency spectrum of blasting vibration, field tests and numerical calculations were combined. The main frequency characteristics of blasting vibration are summarized for five different initiation locations, including the bottom of the charge, the top of the charge, the middle of the charge, simultaneous initiation at the top and bottom of the charge, and simultaneous initiation at two points evenly distributed in the charge section. Based on the spectrum expression of blasting vibration in viscoelastic medium, the characteristics of blasting loads under different working conditions were analyzed from the perspective of superposition of blasting sources, which was used to reveal the influence of detonator arrangement on blasting vibration frequency spectrum. The results show that the initiation conditions are ranked as simultaneous initiation of two uniformly distributed points, middle initiation, simultaneous initiation at the top and bottom, top initiation and bottom initiation, in the order of vibration frequency from largest to smallest. Multiple detonators actually divide the whole charge into several segments, which is equivalent to superposition of multiple sub-explosive sources. Changing the location or number of detonators is essentially to detonate the entire charge in segments at the same time. The more segments, the length of sub-explosive source charge and the detonation process are shorter, which means the energy release rate of explosives and the blasting vibration frequency are higher, and the rise of explosion load is faster. In addition, with the increase of distance to blast source, the influence of detonator position on blasting vibration frequency converges.

Ground blasting vibration control is one of the key contents in the blasting construction of subway tunnels in complex urban environment, and cut blasting is the key to determine the blasting vibration intensity. Combined with the actual project of the north extension line of WuHan Metro Line 7 (Qianchuan Line), an optimization design was carried out on the basis of the original blasting cut method. The numerical simulation and field vibration test verification methods were used to calculate and compare the blasting vibration effects of single wedge cutting, burn cut with four holes and double wedge cutting. Then, the optimization method of cut blasting was proposed. The results show that single wedge cutting, burn cut and double wedge cutting have similar propagation rules of blast vibrations along the axis of tunnel excavation. The peak vibration velocity along the x direction (horizontal radial) decreases with the increase of the distance from the working face in the range of 0~-5 m. When distance exceeds 5 m, the peak vibration velocity increases first and then decreases. The excavated area of the upper bench of the left pilot tunnel has an amplification effect on the surface vibration velocity, which is referred as a “cavity effect”. The distribution of the x-direction (horizontal radial) peak vibration velocity on the left and right sides of the tunnel is roughly similar, and gradually decreases with the increase of the horizontal absolute distance from the origin along the direction perpendicular to the axis of tunnel excavation. The upper bench of the left pilot tunnel has a free face, which makes the peak vibration velocity along the x direction (horizontal radial) on the left side of the tunnel bigger than that on the right side. Due to the delayed initiation, the peak vibration velocity along the x direction (horizontal radial) by double wedge cut blasting is the minimum. The surface vibration velocity of the excavated area is 1.35~2.02 times than that of the unexcavated area ahead during the tunnel blasting construction, due to the “cavity effect”. Compared with other cutting methods, the “cavity effect” of the double wedge cutting is weaker. The comparative analysis of blasting vibration intensity of the three kinds of cutting modes shows that the order of advantages and disadvantages of the three kinds of cutting modes is: double wedge cutting > single wedge cutting > four straight hole cutting.

The authenticity of fracture distribution model is one of the key factors during numerical simulation of blasting in jointed rock mass, which would obviously affect the numerical simulation results. It is hard to represent the complex three-dimensional joint distribution in the existing joint construction method. To explore a simple and feasible operation method for constructing the complex 3D joint model in LS-DYNA software, a K file of blasting numerical model was analyzed and reorganized by MATLAB software. Furthermore, a 3D refined numerical model for jointed rock mass was constructed by the 3D joint distribution law and the constitutive joint model parameters. Finally, a statistical analysis of the three-dimensional joint distribution law was carried out in an open-pit limestone mine, and the joints were reconstructed in the numerical model of a bench blasting. Consequently, a comparative study of the numerical simulation and the field blasting test for open-pit bench blasting was carried out. The results show that the error between the joints built in the numerical model and the actual joints is less than 13%. The joint surface changes the damage distribution of the rock mass. Compared with the intact rock mass, the damage rock mass range increases by 12.04%, and the proportion of fragments with the size of 0~100 mm decreases by 8.11%. The damage results obtained by blasting simulation are close to the field rock breaking effect, and the percentage error of fragments with the size of 0~100 mm is 4.16%. The analytical reconstruction method is feasible and easy to represent the complex three-dimensional joint distribution, and the numerical results are close to experimental results.

In order to solve the existing problems in the explosive welding technology of clad metal plate, such as low utilization rate of explosive energy, environment harm and potential safety hazard, a simple closed explosive charging process, namely a production method of energy-saving explosive welding of clad metal plate, was designed. More precisely, an isolation plate with a thickness about 2 mm was placed on the surface of ordinary explosive, and a 10~12 mm height emery sands layer was laid on the isolation plate. Then, experimental research was conducted to verify the difference of the mechanical properties between the energy-saving explosive welding and the ordinary explosive welding. Non-destructive testing and mechanical properties tests showed that the interface binding strength, binding rate and mechanical properties of clad metal plates produced by the energy-saving explosive welding technology could meet or exceed the technical requirements of the national standard GB/T 8165 and industry standard NB/T 47002. The new method of covering something on the explosive surface can achieve the purpose of saving 1/3 energy compared with the ordinary explosive welding process. And even under the condition of reducing the explosive consumption by 30%, the mechanical performance index of the clad metal is still higher than the national and industrial standards. The experimental results show that the mechanical properties of the clad metal produced by the energy-saving explosive welding process and ordinary explosive welding process are almost the same, which can meet the needs of large-scale chemical equipment manufacturing field. Therefore, the production process of clad metal plate by the method of energy-saving explosive welding is simple, efficient, safe and reliable, and the purpose of saving energy as well as reducing consumption is realized.

In order to solve the problem that excessive blasting vibration affects the safety of village buildings (structures) on the earth's surface during the mining process of an underground orebody, the inter-hole delays of 8 ms, 10 ms, 12 ms, 14ms and 18ms and inter-row delay of 100 ms were selected for tests in the #63113 ore room of the orebody III in the mine. By combining the actual situation of the site and the empirical formula, the natural vibration frequency of the brick-concrete buildings with 1 to 2 floors in the village was 7.63~13.23 Hz. The blasting vibration data was collected on site and HHT transformation was applied on the measured blasting vibration signals by MATLAB. The characteristics of the signals were then analyzed from the perspectives of time domain, frequency domain and energy. The highly adaptive EMD decomposition was used to decompose the original vibration signal into the IMF components which were transformed by 10-layer db8 wavelet transform and the proportion of energy in the total energy of the frequency band 7.8~15.7 Hz of level 9 was summarized. The three-dimensional Hilbert spectrum and marginal spectrum were obtained by Hilbert transformation of the reconstructed signal with the IMF components. Through EMD decomposition and wavelet transform research on the blasting vibration signals, it is concluded that the three-direction energy ratio corresponding to the 12 ms delay time at No.3 measuring point is reduced by 14.07%, 24.89% and 6.26%, respectively. The experiments show that the problem that the problem that the low frequency energy takes a large proportion in the total energy can be improved by optimizing the inter-hole delay, and the resonance effect can be effectively avoided. By comparing the Hilbert marginal spectrum and the three-dimensional Hilbert spectrum with different delay times, the main vibration frequency and the maximum instantaneous energy of the blasting with an inter-hole delay of 12 ms appear 200 ms after the detonation, concentrated in the range of 30~40 Hz which is higher than the natural vibration band of the buildings, and thus have the least influence on the structures.

To explore the mechanical mechanism of burn cut blasting with a large-diameter empty hole, the stress concentration effect of the large-diameter empty hole was studied by theoretical analysis and numerical simulation. Firstly, a mechanical model for the stress concentration effect of the empty hole was established. Furthermore, the empty hole's stress concentration effect was clarified based on the elasticity theory and wave dynamics. A numerical simulation under a typical working condition was then carried out, and finally the stress concentration effect of the empty hole was investigated based on the numerical results of stress wave propagation, rock damage, and the first principal stress. The results show that the stress concentration effect of the empty hole is mainly derived from the stress concentration around the cavity and the stress wave superposition effect. During the blasting process, the stress wave is reflected at the empty hole wall and superposed with the incident wave, which is mostly located in the vicinity of the empty hole and the region between the cut holes. The regions with high damage degree are mainly around the cut hole, near the empty hole, and within the triangle regions formed by adjacent cut holes and the empty hole, and the latter two regions correspond to the stress wave superposition regions. There is a significant stress concentration effect near the empty hole, and the closer the rock is to the empty hole, the more obvious the effect is.

Perimeter blasting is very important to control engineering quality in the process of roadway construction, and it is a common way to use slotted pipe blasting to improve the perimeter blasting effect. However, the unreasonable setting of slotted pipe blasting parameters still weakens the directional destruction effect, including the greatly damaged contour, low hole retention rate, common phenomena of over-excavation and under-excavation. In order to improve the directionality of blasting damage, the slotted pipe blasting parameters should be optimized. The reasonable blasting parameters were determined with the study of explosive slotted pipe uncoupling and different initiation positions by numerical simulation using ANSYS/LSDYNA. According to the numerical simulation results, the balance between the protection of surrounding rock mass and directional failure can be achieved when the uncoupling coefficient between the explosive and slotted pipe is 1.12. Meanwhile, the integrity of the contour line is greatly improved when the initiation positions of two adjacent explosives are changed to make the meeting position of the explosive shock waves on the same horizontal plane that shifted to 3/4 of the position between two blast holes. It can be concluded that the damage to the retained rock mass can be greatly reduced as adopting uncoupled structure between slotted pipe and charge, and changing the meeting position of stress wave between blast holes by adjusting the detonation position of charge.

In channel dredging engineering, the underwater drilling and blasting technology is often used for underwater reefs higher than the designed bottom elevation. However, after drilling and blasting, there are still some rocks that cannot be completely removed and irregular and unstable underwater shallow points remaining. In actual construction, emulsified explosive is often used to remove such isolated stones. Compared with drilling and blasting, adobe blasting has small contact surface between explosive and rock face, large amount of explosive, low energy utilization rate, high explosive consumption, large noise and water shock wave, affecting ecological environment and so on. In order to analyze the influencing factors of shallow blasting, field monitoring research was carried out to compare the adobe blasting underwater and the drilling & blasting method. Under the same effect, the water hammer wave and seismic wave data of CO₂ adobe blasting, drilling CO₂ gas blasting and drilling emulsion explosive blasting were obtained. In this paper, taking the foundation groove, berthing excavation, reef blasting and reef clearing project of 18#~22#berth wharf in Fangchenggang as examples, the arrangement and amount of charge are formulated according to the property of rock strata, rock formation, water depth and shallow point thickness of the blasted rock top. The results show that the overpressure of CO₂ adobe explosion is 1.87~41.9 times that of CO₂ drilling gas explosion under the same cylinder condition. The overpressure of underwater drilling emulsion explosive blasting is 7.9~18.7 times of the water shock wave of CO₂ drilling gas explosion, and the vibration value is 3~10 times of the latter. Based on the research on the propagation law of underwater blast wave, this paper comprehensively analyzes the harmful effect of underwater shock wave.